1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having global word lines connecting a plurality of sectors and local word lines provided in the sectors and a method of controlling the same.
2. Description of the Related Art
Recently, applications of the non-volatile semiconductor memories such as flash memories have drastically expanded. It is known that the flash memory has a cell array of a NOR type, NAND type or AND type. One of the features of the flash memory is to perform erasing on the sector basis. There have been many proposals of the arrangement of sectors. For instance, it is known that the sectors are arrayed in a matrix formation in which the sectors are laterally connected by global word lines, and are vertically connected by vertical word lines. Each of the sectors has a respective local word line with which a connection is selectively made by the global word line and the vertical word line.
The above-mentioned structure has a problem about the reduction of current consumed. The above-mentioned array requires complicated switching, and is likely to waste current such as leakage current. As the capacity of the flash memory increases, the problem becomes more conspicuous.